Dual completion well installation



0. E. DAFFIN DUAL COMPLETION WELL INSTALLATION Feb. 2, 1960 2 Sheets-Sheet 1 Filed June 9, 1958 BY @E/W ATTOR/Vfy Feb. 2, 1960 D. E. DAFFIN 2,923,357

DUAL COMPLETION WELL INSTALLATION Filed June 9, 1958 2 Sheets-Sheet 2 35 INVENTQR.

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United States Patent DUAL COMPLETION WELL INSTALLATION Douglas E. Dafiin, Pasadena, Tex., assignor to Camco Incorporated, Houston, Tex., a corporation of Texas Application June 9, 1958, Serial No. 740,972

6 Claims. (Cl. 166-102) This invention relates to equipment for multiple completion well installations and particularly to an improved well tool receiving and locating mandrel unit for incorporation in common with parallel strings which serve as hole casing and production tubing and through which well fluids may be produced separately from different horizons. Such assembly is especially adapted for permanent well completion practices by which each production string is made up for cooperation with equipment including retrievable tools to be run by means of Wire lines into and out of either or both strings in selective combinations for performance of various working and workover operations while the tubing remains in place. Elimination of the need for tubing string removal from and replacement in the well can avoid the expense and bother of lining a well bore with the usual casing through which additional tubing isplaced for production purposes and an open hole can be wholly or partially filled with cement after the parallel production strings have been lowered to final positions in the drilled hole.

An object of the invention is to provide for the aforesaid purposes an improved mandrel having two sets of top and bottom coupling connections for joinder in end to end succession with a pair of separate production strings and enclosing two fully open tubing bores for coaxial alignment with the top and bottom coupling connections as straight line continuations or parts of the parallel strings with the mandrel having an opening in the wall thereof through which the separate tubing bores can be brought into or closed off from communication with one another in establishing various fiow paths as controlled by selective disposition within the mandrel of different retrievable tools.

A further object of the invention is to provide a dual production tubing mandrel in which each through passage has tool receiving and locating formations and one of the passages has laterally offset therefrom a chamber extension containing another tool receiving and locating formation and all of which formations are for selective positioning special flow directing or blocking tools for co operation with one another and the passages in desired relationships in controlling flow paths through the mandrel.

Another object of the invention is to provide a mul tiple string connector mandrel having a tool receiving pocket laterally offset from the full open bores for enabling controlled flow between the separate conductor strings or for closing them off from one another without obstructing the full open bore of either, whereby well reworking equipment may be lowered below the mandrel and various corrective operations performed through the open bore of a string without disturbing the other string below the mandrel and the producing formation served thereby.

Other objects and advantages will become apparent during the course of the following specification having reference to the accompanying drawings, wherein Figs. 1, 2, and 3 are more or less schematic illustrations showing in vertical section a well installation according to this invention with dilferent arrangements of retrievable tools set in the mandrel unit for illustrating different well working operations; Fig. 4 is an enlarged vertical cross section of the improved mandrel with tools set therein in the manner indicated in Fig. 3 and the section is taken as on line 4-4 of Fig. 5; and Fig. 5 is a transverse section of the mandrel unit with no tools therein and is taken on line 5-5 of Fig. 4.

The mandrel shown in the drawing is to be installed usually a short distance above the uppermost producing zone and as a part of each of multiple tubing strings and consists of a chambered housing in which individual chambers comprising full open bores are provided, one for each of the well fluid production strings for affording separate flow paths to the surface from dilferent producing zones. In shape and form the chambered unit is such that for convenience of manufacture it is made up of generally tubular elements separately worked and later joined together as a unitary final assembly. Such mandrel subassemblies are indicated generally at 1 and 2, positioned in side by side vertical parallelism and secured together by one or more welded connections as at 3.

The subassembly or tubular member 1 is an elongated tube 4 having coupling connections 5 at opposite ends in the form conveniently of exterior screw threads for fastening, as by joint collars 6, in end to end succession to tubing sections 7 of a production string. The central bore or vertical'passage 8 through the tubular subassembly 1 substantially corresponds in size with the internal diameter of the tubing sections 7 and forms a full open bore therewith. The term full open bore as here used means a straight through passage in axial alignment with the tubing sections and normally unobstructed to permit working equipment to be lowered, raised and otherwise manipulated in and through the passage as may be required for performing such wire line and other working as perforating, calipering and various permanent completion operations within the tubing string below the mandrel.

At its upper end the mandrel subassembly 1 has a reduced thickness annular wall 9 ending downwardly in an internal shoulder or landing seat 10 for co-operation with a locating head of any of several standard retrievable well tools. lust below the landing shoulder 10 an internal annular keeper groove 11 is formed in the tubular member 4 for co-operation with retrievable tool latch dogs. Spaced downwardly from the annular keeper groove 11 is another annular groove 12 in line with a lateral port 13 through the wall of the tubular member 4. Above and below the annular groove 12 the interior surfaces of the bore or passage are machined smooth and to a predetermined dimension to serve as sealing surfaces 14 and 15 to be engaged and tightly fitted by mating surfaces of parts such as packing rings carried by a re trievable tool positioned within the passage.

The companion mandrel subassembly is an elongated hollow or chambered housing 16 whose opposite end portions provide top and bottom couplings 17 and 18 (see Fig. 3) for terminal screw threaded connection with adjacent ends of adjoining tube sections 19 of a second production string conduit. This chambered housing 16 is a tubular body which throughout its major extent is widened or of greater diametrical dimension than are its end portions 17 and 18 and the reduced end portions are laterally offset to one side of the longitudinal axis of the enlarged mandrel chamber and are in axial alignment with one another. They are also axially aligned with a straight through passage afiorded by the upper chamber space 20 and its downward tubular extension 21 to one side of an internal housing wall or vertical partition 22 within the lower portion of the mandrel housing 16.

On the other side of the separating partition 22 the housing space affords a retrievable tool receiving pocket 23 in side by side relation with and laterally offset from the extension passage or straight through conductor bore 21. Like the extension passage 21, the offset tool receiver or side pocket 23 is a downward tubular extension of and is in open communication at its top with the enlarged chamber space 20. Both downward extensions are afforded by the formation of the lower housing wall to constitute a pair of side by side tubular bores. The diametrical dimension of the tubular passage 21 vertically aligned with the conductor passage of the remainder of the tubing string substantially. corresponds with the interior size of the tubing string sections for a full open bore as previously defined.

In addition to the top opening by which the side pocket 23 communicates with the chamber 20 and the passage 21, there is provision for communication of the side pocket with the passage 21 at a downwardly spaced point and through one or more lateral ports 24 in the partition wall 22 at the bottom of the pocket 23. At a point intermediate the ports 24 and the open top of the side pocket, the wall of the mandrel contains a lateral port 25 which when the two mandrel subassemblies 1 and 2 are secured by the welds 3 in final assembled relation, is aligned with the aforesaid port 13 and the two ports afford communication between the side pocket 23 and the passage 8. An internal annular groove 26 in the wall of the side pocket 23 is intersected by the side port 25 for co-operation therewith.

At the top of the side pocket 23 the upper edge of the surrounding wall affords a landing seat 27 for a retrievable tool to be fitted within the pocket and a short distance below the seat the wall has an internal annular keeper groove 28 for locating a tool-latch dog. Between the annular grooves 28 and 26 and also between the groove 26 and the communicating ports 24 the wall of [the side pocket is accurately bored and machined, as at 29Z9, to form sealing surfaces for co-oper-ation with packing rings or retrievable tools placed Within the pocket. In like manner the bore of the straight through passage 21 is formed and machined to provide in vertically spaced relation an upper landing seat 30, a latch keeper groove 31, a sealing surface 32, an annular groove 33 intersected by the ports 24 and a sealing surface 34 below the groove 33;

When the mandrel assembly as described is installed in a pair of production tubes and is lowered therewith into a well bore, one of the downwardly projected sections of the tubing will be for co-operation with an upper production zone and the other tubing string will be adjacent and for co-operation with another production zone vertically spaced from the first zone. The mandrel passages and its side pocket can have fitted thereto various flow blocking and flow directing plugs in preselected relationship for the performance of any of different working and reworking operations and it is especially well adapted for permanent dual completions and for use in well bores which are left uncased. When the well bore is not to be lined with well casing, the annular space between the bore wall and the tubing strings may be filled in whole or in part with cement and thereafter conventional wire line operations, including perforating at each of the production zones, can be effected through the respective production strings. Each zone can be independently produced and certain remedial operations '4 can be performed through one string without disturbing the other.

Suitable retrieving tools for disposition within the mandrel according to the job to be done will include by way of example the blocking and flow directing devices shown in Fig. 4 and which are set to blank off the tubing string depending from the passage 8 below the communication ports 13 and 25 and to block off the passage 23 above the ports 13 and 25, and additionally to block off the passage 21 around a hollow retrievable tool above the ports 24- and to provide through the last mentioned tool an extension pipe hung therefrom as a passageway communicating the tubing string at a point adjacent its producing zone with the chamber 20 of the mandrel. In this arrangement, a job can be performed in which a liquid is circulated or pumped from the surface down through one of the strings and crossed over at the mandrel for further downward flow in the other string around the extension pipe and out into the bottom hole with any excess free to move upwardly within the extension tubing and back through the last mentioned string above the mandrel. Such operation, for example, can involve the usual cement squeezing steps wherein a preparatory circulation of washing liquid is followed by the introduction of a given charge of cement slurry with pressure liquid behind the slurry until the latter is delivered below the extension pipe 35. After squeezing pressure has been applied, a wash liquid is circulated,

usually in a reverse direction, to carry through the tubing any residual or excess cement.

As shown in Fig. 4, the extension tubing 35 is coupled at its .upper end to a hollow hanger or retrievable tool 36 and. communicates with the chamber 20 through a hollow core which has a short slide travel within the body of the hanger 36. This body mounts annular packing rings 37 for co-operation with the sealing surfaces 32 and has at its upper end an annular head 38 to seat on the landing shoulder 30. It carries a number of latching dogs 39 which are laterally retractable and projectable into and out of the keeper groove 31, the action of the dogs being responsive to the projection and retraction of the center core within the body according to conventional retrievable tool structures. The body 40 fitted to the passage 23, and the body 41 fitted to the passage 8 both similarly include a central slidably positioned core by which latch dogs 42 and 43, respectively, can be projected and retracted from the co-operating keeper grooves 28 and 11. An enlarged head 44 on the body 40 engages with the landing seat 27 and exterior packing rings 45 engage the sealing surface 29 against fluid flow upwardly through the side pocket when the retrievable plug is in place. In this case, the interior of the plug is closed by a bottom cap 46. The retrievable tool body 41 has an upper head 47 for co-operation with the landing seat 10 and has packing rings at 48 and 49 for co-operation with the sealing surfaces 14 and 15. Its hollow interior is closed by a bottom cap 50 and between the spaced apart packings 48 and 49 its side wall has one or more side windows 51 aligned with the annular groove 12 for communicating the side port 13 witlli the tubing above the flow blocking and directing too Conventional wire line running tools are used to lower the tool body 41 through the tubing string above the mandrel tube 8 and after the tool has been landed the running tool is actuated to depress the central core for projecting the latches 43 and then releasing the running tool for return to the surface. Later, a pulling tool can be lowered and brought into locking engagement with the central core for first raising the core to allow retraction of the locking dogs 43,. followed by the elevation of the entire tool back to the surface. Similar running and pulling tools are employed with the tubing string above the mandrel subassernbly 2 for setting and removing the flow controlling tools within the passage 21 and side pocket, depending'on the type of operation to be performed. Thus an extension tube similar to that shown at 35 in Fig. 4 can be suspended from a hollow hanger positioned as shown at 52 in Fig. 2 within the mandrel passage 8. When the other mandrel passage 21 is additionally blocked by the reception of a retrievable tool 53 having sealed relation with the surfaces 32 and 34 above and below the side ports 24, a liquid can be circulated or pumped down the tubing string and deflected for flow through the pocket 23 and through the lateral ports 13 and 25 into the annular space around the tubular extension hung within the mandrel tube 8 and sealed at 14 for downward flow to the production zone and back up through the return hollow extension tube and extension tube hanger into the tubing string above the hanger. A cement slurry can follow the same path for delivery to the formation level and there subjected to a squeezing pressure by proper control of surface valving and pressurization of the liquid columns standing in-both tubing strings. Removal of excess cement is by entrainment in washing liquid, usually circulated in the reverse flow direction.

Removal of retrievable tools from the mandrel passages 8 and 21 provides continuous full open bores throughout the length of the tubing strings, inclusive of the passages through the mandrel. The lower end of either tube can be suitably perforated in the usual fashion by passing perforating equipment through the full open bore down to the desired level. Also, other operations, including the removal of paraffin accumulations and fluid flow, either upwardly or downwardly, can be effected through the full open bore. Usually at such times as work is being performed in either tubing string below the mandrel, there will be positioned within the side pocket a suitable retrievable tool, such as indicated at 54, which will carry packing rings to co-operate with the sealing surfaces 29 above and below the intermediate communicating ports 13 and 25 so as to close off the production strings from one another. This arrangement is illustrated in Fig. 1 and also represents the situation which exists when either or both zones are being pumped or produced, so that production fluids through the separate strings do not commingle with one another.

Only a preferred embodiment of the invention has been specifically described and it is to be understood that such modifications can be made as come within the scope of the appended claims.

What is claimed is:

1. In a permanently completed dual production well, a pair of production strings arranged to be cemented one beside the other within a well bore for communication with different production zones, a mandrel connected in common with both strings and provided with a pair of parallel through passages one aligned with and formed as a part of a straight through tubing bore of one string and the other aligned with and formed as a part of a straight through tubing bore of the other string, a pocket in said mandrel laterally offset from both of said straight through tubing bores, said pocket having communication at vertically spaced apart points with one of said tubing bores and at a point intermediate said spaced apart points with the other tubing bore and a series of retrievable blanking-off plugs selectively positionable in said pocket and said passages and adjacent said points of communication for co-operation therewith in the control of flow through the mandrel in various relationships including noncommingling flow through either passage and flow from one passage to the other.

2. A tubing string mandrel for use with dual com{ pletion wells, including a housing unit, twosets of ver-' ticallyaligned top and bottom connections on said unit for coupling the same in two production strings, a first passage having a full open bore extending on a straight line between the aligned connections of one set, mounting means in the last mentioned bore for receptionof a retrievable tool, a second passage havinga full open bore extending on a straight line between the aligned connections of the other set, mounting means in the last mentioned bore for reception of a retrievable tool, a flow connection communicating with said passages intermediate said top and bottom connections and being positioned in laterally ofiset relation to both passages and mounting means in said How connection for reception of a retrievable tool, said several mounting means being arranged for eo-operation with different retrievable tools selectively positionable therein for variously blanking 0E portions of the first and second passages above and below said flow connection and for intercommunicating the first and second passages for flow in any of several diiferent paths from one to the other.

3. For use with dually completed wells, a mandrel unit having one set of opposite end connections for coupling with one production string and a straight through open bore aligned with said connections and having another set of opposite end connections for coupling with another production string and a straight through open bore aligned with the last mentioned opposite end connections, port means in the mandrel unit communicating with both bores and a tool receiving keeper carried by the mandrel unit adjacent said port means and laterally ofiset from both sets of end connections in bore clearance relation for the removable mounting by said keeper of a retrievable tool in the selective control of communi cation through said port means and tool locating formations in said mandrel at each of said open bores for selective reception therein of retrievable tools in the further control of communication of said open bores one with another.

4. For use with dually completed wells, a mandrel unit, a pair of separate chambers therein for connection with dual production tubing strings, each chamber having axially aligned and vertically spaced apart connector portions for coupling with a tubing string and also having an open bore in coaxial relation with said axiallyaligned connector portions to provide an unobstructed path through the mandrel unit for travel therethrough of well working tools, one of said chambers having a lateral extension oflset from its open bore and in communication with both bores and plug receiving means within said extension and within each of said bores respectively for sealing engagement selectively with retrievable plugs in selectively blocking off and controlling direction of flow communication through said lateral extension and from one to the other of said bores.

5. For use with dually completed wells, a mandrel unit enclosing a pair of separate chambers for connection with parallel tubing strings and each chamber including vertically aligned top and bottom string coupling portions and a passage extending on a straight line axis coincident with said aligned coupling portions and providing a full open tubing bore through the mandrel unit for passing well working equipment, one of said chambers having a lateral extension offset from its chamber passage, a retrievable tool receiving pocket in said lateral extension having top and bottom communication means with one passage and communication means with the other passage at a point intermediate said top and bottom communication means, sealing surfaces on the I interior of said pocket between the several communication means for co-operation with retrievable tools removably positioned within the pocket and a series of retrievable tools positionable individually in said pocket and said passages in selective relationships for blocking and di- 7 resting fluid flow in any of several combinations within the mandrel.

6. The structure of claim '5 wherein said one passage has tool engageable sealing surfaces internally thereof above and below the bottom communication means and said other passage has tool engageable sealing surfaces internally thereoflabove and below the intermediate oommunication means.

References Cited in the tile of this patent UNITEDISTATES PATENTS Tau'sch Dec. 4, 1956 Anderson et.al. Sept. 17, 1957 'Tausch Feb. 4, 1958 Dafiin et al. Aug. 5, 1958 Brown Sept. 2, 1958 

